How Good Are Those IR Thermometers For Checking For Fever?
hubie writes:
It is fairly common these days when visiting a doctor's office or entering a port of entry to have one's forehead scanned by a Non-Contact Infrared Thermometer (NCIT) to check for fever (temperature greater than 38 C). The measurements are typically very quick and easy to make. NCITs are not as accurate as contact thermometers, so it is important to know whether convenience is being traded for accuracy.
NCITs measure forehead temperature by detecting infrared radiant energy. Since the temperature of the forehead skin is lower than the core body temperature, the device manufacturers use propriety algorithms to correct for this. Depending upon the device, it might also factor in the ambient measurement conditions such as the room temperature and skin emissivity. These devices may give erroneous results from not only issues with the hardware or algorithms, but also in how they are used (pointed too far away or at the wrong angle), or the local conditions of the forehead skin (local heating or cooling from sweat or moisture). FDA approved devices conform to voluntary standards that specify they should be within 0.3 C of a laboratory source.
FDA researchers measured oral temperatures from more than 1000 subjects using a clinical-grade reference thermometer and compared that to measurements made at the center of the forehead using six different models of NCITs. Although it is expected that the variability in a clinical setting would be larger than in the lab, they saw that the error can range from -3 to+2 C in extreme cases, with the majority of the errors ranging from -2 to +1 C.
Overall, our results indicate that some NCIT devices may not be consistently accurate enough to be used as a stand-alone temperature measurement tool to determine if the temperature exceeds a specific threshold (e.g., 38 C) in an adult population. Model-to-model variability and individual model accuracy in the displayed temperature are a major source of concern. Users should be aware of the consequences of false negatives and false positives when using NCITs as a screening tool.
Journal Reference:
Sullivan, S.J.L., Rinaldi, J.E., Hariharan, P. et al. Clinical evaluation of non-contact infrared thermometers. Sci Rep 11, 22079 (2021).
DOI: 10.1038/s41598-021-99300-1
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